The present invention is directed generally to a three-phase motor and, more specifically, to a method and a quick-disconnect apparatus for disconnecting and reconnecting power to a three-phase motor.
Much of today's heavy duty machinery requires three-phase power. Examples include motor-driven pumps, motors and generators in power plants, refineries and steel mills. In addition, the cables necessary for providing adequate power to the machinery must be extremely large to accommodate the massive currents used in some of the three-phase motors. As a result, many three-phase motors used to operate heavy duty machinery require a number of very bulky, large and inflexible cables.
Several problems are known when dealing with such a large number Of missive power cables in a large heavy industry plant especially when several three-phase motors are in use. For example, large cable trays are used to guide the cables between pieces of equipment and the main power supply for the equipment in the plaint. While these cable trays are able to keep a large number of power cables neatly organized from the power supply to the individual motors and other pieces of equipment using three-phase power, other problems are commonplace.
For example, it is a known problem at the actual motor itself, where the cables leave the cable tray and are loose, to provide an acceptable solution for organizing and connecting the cables. The large cables are bulky and less flexible and as a result cause difficulties in organizing and connecting the cables at the three-phase motor. In addition, to complicate matters, some heavy duty motors require very large currents that are beyond the capability of the standard power cables. Thus, in these instances, a particular motor will require a parallel feed of three-phase power. Thus, the number of power cables is at least doubled to provide the adequate current needed for the three-phase motor.
In addition, some of these motors can be as large as a tanker trailer on a semi and have horsepower ratings of several thousand horsepower. As a result, typically many heavy-duty motors require connections to several bulky power cables at a junction box for the motor. These cables are often spliced together (known as "bugging") with heavy-duty rubber tape and PVC tape. However, these spliced cables form an unwieldy bundle at the motor that is difficult to work with and cumbersome to disconnect (i.e., "un-bug"). For example, if a motor needs to be replaced, a time consuming disconnection of the spliced together massive power cables ("un-bugging"and "re-bugging") greatly increases the time needed to replace the motor. For example, a typical "un-bugging" procedure requires a full shift for two skilled workers. In addition, a typical "re-bugging" procedure requires a shift and a half for two workers.
Thus, a method and apparatus for providing quick-disconnects for efficiently and neatly disconnecting power to a three-phase motor (un-bugging and re-bugging) is needed in the field of heavy industry.